So I've just got the A6500 from Sony for making video. The 18-105 f4 has been perfect for all my filming so far but with winter coming I need to get some faster glass to get some more light in on these dark nights. Have some questions...

If you put the Sony 35mm 1.8 with stabilisation on the A6500 with stabilisation do both stabilisers work or does one switch off the other?

Is the f1.4 from sigma in real-world terms going to let much extra light in compared to the Sony f1.8?

Sony E 35mm f1.8 is the only APS-C lens with full support for the hybrid autofocus found in A6x00 cameras. Sigma lenses on the other hand, have very reduced hybrid af performance. That is important as hybrid af is the main selling point of Sony mirrorless cameras.